Piston expander



W" 24, 1934- A. w. MORTON 1,956,328

PI STON EXPANDER Filed Dec. 16 {1933 2 Sheets-Sheet 1 SK 5 I E ,4 132+,f i

3uventor;

" mum w. mlozkon/ (Ittornegs April 1934a A. w. MORTON 1,956,328

' PISTON EXPANDER Filed Dec. 16, 1933 2 Sheets-Sheet 2 Ismaentor BB k(Ittornegs Patented Apr. 24, 1934 PISTON EXPANDER Allen W. Morton,Baltimore, Md., assignor to The American Hammered Piston Ring Company,Baltimore, Md., a corporation of Maryland Application December 16, 1933,Serial No. 702,775.

9 Claims.

This invention pertains to expanders for pis-- tons of the split skirttype, which are now commonly employed in explosive engines, and moreparticularly those designed for automotive purposes.

The main object of the invention is to produce a simple and yet withaleffective expander, the same being produced from spring wire and soshaped or bent to form as to produce the necessary or requisite outwardpressure upon the inner face of the skirt, to expand the same.

The structure is such that the expander may be readily positioned withinthe piston, and, when fully positioned, will automatically pass into theslots or openings normally existing in pistons of the type abovereferred to, and thus lock the parts against relative endwise movementwhile still permitting the expander to act v to force the sections ofthe piston skirt outwardly.

Another advantage of this type of expander, owing to its contour, isthat it can be made to exert the greatest amount of expansion at thelower portion or near the end of the piston skirt, and a secondary orless amount of expansion at the upper portion of thelskirt, or thatportion opposite or slightly above the piston pin bosses. Collapse atthe bottom of the piston is frequehtly caused by the rocking action ofthepiston, but this may be corrected to a large extent by the use of anexpander such as hereinafterdescribed.

Yet another advantage is that the expander mary or maximum pressure maybe obtained at the top portion of the piston skirt, or nearly in theplane of the piston pin, and the secondary pressure at the lowerportion, or near the end of the piston skirt.

Still another advantage of the type of expander herein set forth is thatthe length of the main body portion, which serves to exert or impart thebulk of the spring action to the structure,. can be so varied as toexert the desired degree of pressure against the piston skirt.

With theseand other objects and advantages in view, reference will behad to the annexed drawings, wherein:

Figure 1 is a perspective view of the preferred form of expander;

Fig. 2 is a top plan view thereof with the expander shown as partiallycompressed prior to its introduction into a piston;

Fig. 3 is a vertical sectional view of a split skirt piston with theexpander of Fig. 1 fu11y posican be positioned within a piston so that apri-.

tioned therein, the section being taken on the line III-III of Fig. 4;

Fig. 4 is a like view taken on the line IVIV of Fig. 3;

Fig. 5 is a perspective view of a portion of a piston and the closedlooped end of the expander, and illustrating the manner of engagement ofsaid end with the piston;

Fig. 6 is a perspective view of a modified form of the expander;

Fig. 7 is a vertical sectional view on the line VIIVII of Fig. 8, of apiston with the expander of Fig. 6 shown as positioned therein; and

Fig. 8 is a like view on the line VIII-V1II of Fig. 7, looking towardthe left of said figure. Under both forms, it will be seen that theexpander is shaped from a single piece of wire, such as spring wireproduced from a suitable heat resisting alloy, so that the expander willretain its resiliency notwithstanding the high and varying temperaturesto which it is subjected when in use.

In a broad sense, the expander may be said to comprise two arcuate orsubstantially bowshaped body members which stand in approximateparallelism, and which are connected at one end by a loop-like pressureapplying element, while at the opposite end of each loop there is 7formed a bearing or pressure arm, the various parts being formedintegrally. 35

In the drawings, Figs. 1 to 5, 10 and 11 indicate the main arcuate bodyelements or bows which, when the expander is positioned within a pistonskirt, extend transversely thereof with the bows directed upwardly. 90

The members 10 and 11 at the lower portion of one end thereof are curvedinwardly, as at 12 and 12 and from such portions there extends upwardlya closed loop formed bythe members 13 and 14, connected by the crossbaror element.15.

As will be seen upon reference more particularly to Figs. 1, 3 and 5,the upper ends of the members 13 and 14 where they merge into thebar-like element 15 are bent outwardly to a slight extent (see Figs. 1and 2). Said bar-like member 15 is slightly curved in outline andprovided with a flat upper face 16 which, when theexpander is positionedwithin the piston skirt, permits the bar to pass into a slot, such as17, formed in the skirt 18 of the piston which is split longitudinallyat least at one side, as at 19.

The thickness of bar 15 is such that its upper flattened face bearsdirectly against the upper no wall of slot 17, and likewise by reason ofthe curvatures above mentioned, the bar also contacts the lower wall aswell. In other words, the bar may be said to have a wedging connectionwith the piston by reason of the formation just described.

As will be seen upon reference to Fig. 3, the bar-like member 15 doesnot extend out beyond the face of the skirt, and is so positionedbeneath the ring belt of the piston that there is no outward projectionat this point.

At the opposite end of the expander and extending upwardly from thelower end of the member 10 is a bearing arm or element 21, formed byrecurving or bending the wire upon itself, as at 22. At its upper end,the member 21 is provided with a single lateral projection 23 extendingoutwardly therefrom, the upper face whereof is flattened at 24. Asimilar arm is formed upon the member 11, and like parts are indicatedby the same reference numerals with the exponent a added thereto. Thefingers 23 and 23 will, when the expander is positioned within thepiston skirt, extend into a second slot 17, which is ordinarily presentin the commercial pistons of today, the fingers being so proportioned asto make a tight or close fit with the walls of the slot.

To position the expander, it is only necessary to compress the same byforcing the arms 21 and 21 toward the bearing members or arms 13 and 14.This collapses the expander to a sufficient extent to permit it to bemoved upwardly into the piston, in the position shown in Fig. 3, whenthe cross bar 15 will enter, or may be forced into the slot 17 and thefingers 23 and 23 will be positioned in the slot 1'7, in a like manner.

The upper and lower portions of the members 13, 14, 21 and 21 move outinto contact with the inner wall of the piston, and at the same time,the bar-like element 15 and the fingers 23 and 23 will enter the slots17 and 1'7 in wedging relation therewith.

The structure is thus locked against endwise movement relative to thepiston, and this condition obtains under all operations of the engine.The bearing portions of members 13, 14 and the interconnecting cross bar15, together with the bearing portions of arms 21 and 21 will at alltimes exert an outward pressure upon the piston skirt.

It is preferable to have the arms 21 and 21- positioned to either sideof the vertically disposed slot 19, as best shown in Fig. 4. Under thisarrangement, a direct pressure is exerted upon the skirt to either sideof the slot and expansion of the piston skirt, therefore, is morereadily obtained.

The expander, of course, may be turned end for end and installed in thepiston so that the members 13 and 14 straddle the slot 19 of the piston.

In the broader aspect of the invention, the structure shown in Figs. 6,'7 and 8 may be employed, and the same principle of utilizing thearcuate expanding members carrying at each end bearing members, ispresent. The expander is automatically locked in position by engagementof portions thereof with the walls of the usual horizontally disposedslots, as in the structure above described.

As will be seen upon reference to Fig. 6, there are two inverted arcuateor bow-shaped members 30 and 31, said members at one end being bent orturned inwardly as at 32 and 33, and from the inner ends of theseinturned portions there 5X- tends downwardly an integrally formedloopshaped bearing element 34.

The upper ends of the inturned portions 32 and 33 are flattened as at 35and 36, respectively, in order that the inturned or bar-like portionsformed at this point may enter the horizontally disposed slot 17 formedbetween the piston skirt and the ring belt of the piston. In otherwords, this slot is the same as the slot 17 in the structure abovedescribed.

The arcuate member 30 is provided with a downwardly extending arm 3'? atthat end opposite the loop-shaped element 34, the connection between theupper portion of the arm and the upper end of the arcuate member 30being defined by a bend or cross bar 38, which is flattened upon itsupper face as at 39.

Member 31 is also provided with an arm formed in the same manner as thatjust described for the arcuate member 30. Similar reference numeralsappear upon the same parts, with the exponent a added thereto.

It will be noted upon reference to Figs. 6 and 8, that the arms 3'1 and38 are spaced apart and when the expander is positioned within thepiston, they bear against the skirt to each side of the longitudinallyextending piston slot 19. So, too, the recurved or inwardly extendingportions 32 and 33 do not contact each other, and this separation of thearms and the elements just mentioned affords a flexibility to thestructure which might not otherwise obtain.

When positioned within a piston, the flattened faces 39 and 39 formedupon the bars 38 and 38 extend into the horizontally disposed slot 17 Byutilizing the ordinary slots 17 and 17 commonly found in pistons of thesplit skirt type, in which the locking elements of the expander mayenter and wedge, all relative movement of the parts, when the engine isin operation, is obviated.

Hence, there is no wear imposed upon either the piston or the expander,and the expander always exerts the necessary and requisite pressurethrough the bearing members formed at each end of the arcuate orbow-shaped elements.

Under both forms, as shown and described, there is no contact betweenthe incurved portions which connect the members forming the loopshapedbearing element, nor is there any contact between the arms 21 and 21 andthe corresponding elements 37 and 3'7 of Fig. 6.

By reason of the separation of the arms at the free ends of the arcuatemembers, not only do the arms act to force or-expand the piston skirtoutwardly in the direct line of contact, but there is also a slighttendency for the arms to move over the inner face of the piston awayfrom each other. Thus it may be said that a pressure exists which is thecomponent of the direct pressure and the pressure which obtains by themovement of the arms away from each other, as the piston is expanded.

It is to be noted that the main supporting or bow-shaped elements 10 and11, 30 and 31 do not come into direct contact with any portion of thepiston and, consequently, the only heat which reaches the spring portionof the expander is that transmitted through the skirt and the ends ofthe expander to the central portion or bowshaped members. Hence, theliability of the spring losing its tension due to heat is greatlydiminished. The expander can also be used in a greater number ofdifferent pistons than most expanders of commercial success, only fivesizes of the expander being necessary to take care of practically all ofthe automotive piston sizes now currently in use.

I am aware of U. S. Letters Patent No. 1,428,492 to Page, datedSeptember 5, 1922, which patent is now owned by the assignee of thiscase.

What is claimed is:

1. An expander for pistons of the split skirt type, the same beingproduced from a single piece of spring wire bent to form a pair oflaterally displaced bowed or arcuate elements;'a pressure applying loopformed at and connecting adjacent ends of said elements; and an armextending from the opposite free end portion of each bowed element, saidloop and arm being adapted to bear against the inner surface of thepiston skirt when I the expander is positioned therein undercompression.

2. A structure as set forth in claim 1, wherein those portions of theexpander which align with the usual slots which are present between thepiston ring belt and the upper portion of the skirt in a divided skirtpiston, are so shaped that they pass into said slots, into contact withthe upper and lower surfaces which define the slots, when the expanderis fully positioned within the skirt.

3. An expander for pistons of the split skirt type, said expander beingproduced from spring wire, comprising in combination two arcuatemembers, each of which is provided at its ends with a bearing member forcontacting the inner face of the piston skirt, said members beingproduced by bending the wire of which the arcuate members are formedback upon itself; and one pair of adjacent bearing members beingintegral with each other and the arcuate members, and serving toposition the two arcuate resilient members with reference to each other.

4. In combination with a piston having a divided skirt and the usualopenings extending between the skirt and the piston ring' belt, anexpander for the skirt, comprising a pair of arcuate members, saidmembers at one end being interconnected by a loop which bears directlyagainst the piston skirt, while the other end of each of said members isprovided with a bearing arm, said arms being spaced apart and bearingupon the inner face of the piston to each side of the longitudinallyextending dividing slot formed in the piston skirt.

5. A structure as set forth in claim 4, wherein the loop and the armsare provided with projections adapted to pass into the slots formedbetween the piston skirt and the ring belt of the piston and intocontact with the upper and lower walls of the slots, whereby theexpander is held against longitudinal movement relative to the piston,while still permitting the expander to act to enlarge the skirtdiameter.

6. In combination with a piston having a ring I belt, a divided skirtand slots formed between the upper edges of said skirt and the ringbelt; an expander for the piston skirt, said expander comprising twoarcuate shaped elements; formed at one end of said arcuate members, saidloop at its upper portion being curved slightly in an outward directionand having its upper face flattened, the opposite end of the arcuatemembers being inwardly curved and terminating in pressure arms'extendingupwardly from said curved portion, said arms being free of anyconnection with each other, and provided at their ends with outwardlyextending projections, said projections and the flattened portion on theloop aforesaid being adapted to enter and wedge in the slots whichunderlie the head above the skirt.

7. An expander for pistons of the split skirt type, comprising a loopshaped member; means thereon for interlocking it with such a piston; apair of upwardly extending arcuate shaped members interconnected withthe lower ends of said loop by incurved portions at the bottom of theloop; and a pair of spaced arms extending upwardly from the oppositeends of said arcuate shaped members, said arms having means on the endsthereof for attaching them to the piston.

8. An expander for pistons of the divided skirt type, the same beingproduced from a single piece of spring wire bent to form a pair oflaterally disposed, downwardly extending bowed or arcuate elements; apressure applying loop formed at and connecting a pair of adjacent endsof said elements, the interconnecting portions of the loop to thearcuate members being flattened upon their upper faces; a pair ofpressure arms extending downwardly from the other end of the arcuatemembers, the portion which connects each arm to its arcuate member beingflattened upon its upper face, said arms being out of contact with eachother and' the connecting portions of the loop aforesaid likewise beingout of contact with each other.

9. In expanders for pistons of the divided skirt type, the same beingproduced from a single piece of wire bent to form a pair of arcuateshaped members; piston-contacting elements carried at the opposite endof each of said arcuate members, said piston-contacting members bearingat their upper and lower ends only against the inner face of the skirt;and means formed upon the expander for entering openings normally foundin the piston beneath the ring belt for locking the expander in placewithin the piston.

ALLEN W. MORTON.

a loop-

